Telegraphy



G. C. CUMMINGS.

TELEGRAPHY.

APPLICATION FILED JULY 16, ms.

Patented Sept. 7,1920.

//4 [/6 n 72/ 060/76 6. Cum/whys.

UNITED s'rarss P ATENT oFFIcE.

GEORGE O. CUMMINGS, OF ORANGE, NEW] JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NE'VV YORK, N. 1., A CORPORATION OF NEW YORK.

1,352,116. 7 i Application filed July 16,

T 0 all 107L027). it may concern Be it known that I, GEORGE C. CUMMINGS, a subject of the King of Great Britain, residing at East Orange, in the county of Essex, tate of New Jersey, have invented certain new and useful Improvements in Telegraphy, of which the following is a full, clear, concise, and exact description,

This: invention relates to telegraph systems and more particularly to systems for rendering secret telegraphic service.

The principal object of this invention is to provide an improved organization of apparatus to render more effective and efficient service in the application of 'cryptog' raphy to the handling of telegraphic mes-- sages.

In connection with messages of a confidential nature, it is, in general, the accepted practice to employ so-called fixed forms of secret codes in seeking to render .such messages intelligible only to an addressee or to certain attendants at telegraph stations; In the use of such codes it is well understood that a message is first codified and transmitted in such cryptic form, following which it must be deciphered or dedecoders, it is nevertheless well understoodthat practically any fixed secret code may be readily analyzed and deciphered by an expert cryptogrammatist. When the possibility that such experts may secure access.

' K with the contingency'thatot to code messages is considered in connection hers may surreptitiously obta n the necessary informationv or key whereby code may be, de-

' ciphered the conclusion is warranted that in general fixed codesmay be considered as inadequate to'afiord the secrecy desired.

Since fixed" codes may be considered as relatively unreliable, anfalternate method for safeguarding the secrecy of telegraphic communications may be provided by rarranging that extraneous jor heterogeneouscombinations of current impulses may be superimposed upon a telegraphic circuit in such a manner that message impulses transmitted over the same circuit will be inter- Tennessean Specification of iet'ters Patent.

form either 'lay' 10.

Patented Sept. *7, 1920.

1918. Seria1No. 24-5,144. I

spersed between the extraneous currents or differential or accumulative electrical effects therewith in the line conductor circuit. By this arrangement line currents may be'rendered intricate and irregular and of such cryptic form that the efiorts of expert cryptogrammatists may be effectively baffled, while no decoding or key information would be possible for the use of persons who may unauthoritatively out in on or tap'a telegraphic circuit.

To the end that the foregoing cryptographic eflects may be attained, the present inventioncontemplates the employment of means for transmitting heterogeneous combinations of currents to and fro over a line circuit and to providing electro-responsive'equipments whereby message impulses impressed on the same line conductor may be screened out or differentiated from said heterogeneous currents with respect to suitable telegraphic receiving de- This invention is illustrated diagrammatically in the accompanying drawing and, for the sake of clearness, only so much of a telegraphic system has been shown as willbe necessary to a ready and clear understanding of the features of the system.

In the drawing, Figure 1, is shown an equipment suitable for carrying on cryptic telegraphic service in accordance with this 1I1V6I1't1011, while in Fig. 2 there is shown an alternate arrangement for controlling certain portions of the circuits'more directly relating to the receiving devices.

In describing the operation of this system,

attention will first be directed to Fig. l of the drawing. Equipment indicated by the reference character A may be understood as present at-a first telegraphic station. while an equipment indicated by the reference character B may be considered as present at a second telegraphic station. Disregarding for the moment the secret service features of this system, at the station A, a transmitting key 1 controls pole-changer relays 2 and 3 inwestablishing changes of current polarity'from two line batteries 5 and-6 with the "contact stops of a polar re- The armature .or moving contact member 11 of the relay 10 is connected to J i the apex or neutral point of a duplex equipment formed by this relay, an artificial line AL and amain-line conductor L, the lead to the artificial line being routed through one winding of a second polar relay 15, while the lead to the real line L is routed through a second windin of this relay.

As well understood in the art, changes of current polarity controlled by the key 1, although balanced and rendered non-efiective with respect to the relays and 15, may become effective over the line L to cause a relay at the distant station B to reciprocate its armature in phase withthe polarities of such transmitted impulses. A circuit under control of the relay 20 includes the contacts of a polar relay 23, a battery 26, the winding of a relay 27 and an impedance uni" 28. it will be seen that the contacts of the relays 20 and 23 are interconnected in such a manner that a so-called three-way switching relation may be efl'ective with respect to these relays in their control of the relay 27. The relay 27 is arranged to control the operation of a suitable receiving device 30 which may, for convenience, be in the form of a reading sounder. A resistance unit 29 is connected across a loop formed by the winding of the relay 2'? and the impedance 28 in such a manner that it may act with the impedance 28 to set up a lagging or retarding effect with respect to the operating time constant of the relay 27 to more particularly compensate for slight differences in the time phase of operation of the relays 20 and 23, for reasons as will presently appear.

For the purpose of transmitting message signals from the station 13 to the station A, a switch 31 may be moved to its closed position, thereby rendering a transmitting key 32 effective to control the operation of a polechanger 83 whereby the associated 0pposi3ely poled sources of current 36 and 37 may be applied to the neutral point of the differential duplex equipment formed by the relay 20, the artificial line AL and the real line L. Such current changes although nonelfective in the relay 20 may traverse the line L and disturb the balance of the relay 15 at the station A and cause the armature of this relay to be reciprocated in phase with the polarity of these currents and thereby effect the operation of an associated receiving device or sounder 16.

ring the time messages may be under trai'zsinission from the station A to the stati-o'ri B as described, application of the secret serrice features of this system may be had b opening the switch 31 at the station 13 and setting in operation a group of trans mitting contacts 40 which may be ofsuch form to come under the control of a d or suitably perforated tape, as well eistood in the art.

connection with the operation of the i ter a0, a distributor comprising five menus ll, collector ring 42, and a contactor or trailer brush. 43 is also operated (by means not shown) to travel in the direction of the arrow in successively completing a circuit whereby the battery 34L may act through selectively closed ones of the transmitter contacts 40 and the respectively associated segments 41., collector ring l, polechanger 33, and the normally closed key 32. This operation of the transmitter 40 and distributor equipment will cause the polechanger 33 to transmit impulses from the batteries 36 and 37 outwardly over the line circuit L, asalready described in connection with the key 32.

In addition to traversing the duplex equipment formed by the real line L and the artificial line AL, these transmitted currents may also divide over a branch circuit formed through a conductor 50, an impedance 51, a polar relay and a resistance 52, to earth. The impedance 51, resistance 52 and a condenser 53 and resistance 54 may be understood to constitute a suitable network the electrical characteristics of which may be Varied in such a manner that the re lay 5:3 in its responses to changes in polarity of the transmitted currents may be retarded to the extent that the responses will not act in phase with the effect of these currents in flowing outwardly over the real line L, the reasons for which will presently appear. On arriving at the distant station the impulses initiated by the transmitter 40 cause the operation of the relay 10. As will be noted, the armature 11 of this relay, under operation, may alternately establish changes in current polarity from the batteries 5 and 6 with the neutral point of the duplex equipment at this station. Such current changes accordingly represent a retransmission of the impulses originating at the transmitter 40 and these impulses in returning over the line L cause the armature of the polar relay 20 to be reciprocated in phase with their polarities.

The contact stopsof the relay 55 are connected to oppositely poled batteries and, since the armature of this relay is connected to complete a circuit through the windings of the relay 23 and an associated resistance, it will be clear that the armature of the relay 23 will be reciprocated in unison with changes of polarity through its operating circuit as established by the relay 55.

In establishing the lagging or retarding of the relay 55, this effect shou d be timed so that this relay will respond in such phase with the operation of the relay 20 as effected hy the retransmitted or returning impulses, that the resulting responses of the relay may be relatively in phase with the response or". the relay 20. Therefore, the operating relation of the relays 23 and 20 will be such that, in respectively responding to transmitted and returning impulses, they will line conductor L, operation of the transmitting key 1 'at the station A will also effect with res Ject to the negatively poled battery second station. Therefore the 11116,,

changes in polarity with respect to the retransmitting armature 11 of the relay 10 and such changes of polarity become effective over the line conductor L toaffect the relay 20 in such a manner that the local circuit which includes the relay 27 will be controlled. in phase with the changes of polarity set up by the pole-changers 2 and 3 under control of the'key 1. Therefore, these effects on the relay 20 may, in turn, work the sounder 30 to reproduce a message transmitted from the first station.

In order to more specifically describe the various relations of the message and nonmessage impulses a few examples will now be assumed and considered. Accordingly, during the time the transmitting key 1 at the station A may be idle, and the pole changer 33 at the second station positioned as shown in the drawing, the negatively poled battery 5 at the first station will be connected over'the contacts 12 of the relay 10 and thereby form a differential balance 36 at the v relays 10 and 20 at the respective stations will stand biased to their negative positions shown in the drawing. At the 'second station'the circuit for the sounder control re lay 27 will at such times be completed through contacts 21 and 24 of polar relays 20 and 23, respectively, since the battery 36 will effect negative bias of the polar relay 55 which in turn establishes a corresponding bias of the relay 23. If now the pole changer 33 is operated the positively poled battery 37 will form an accumulative series with the negatively poled battery 5 at the first station, and this current will cause the armature 11 of relay 10 to assume its opposite or positive bias, thereby connecting the positively poled batteryfi over the contacts 13 to the apex of the duplex equipment, thus establishing a differential effect with the battery 3'? at the distant station and accordingly the line relay 20 will assume its opposite or positive bias to close its contacts 22. In phase with this operation, current from the battery 37 acting through therelay '55 will have established opposite bias of this relay to correspondingly bias the relay 23 to separate its contacts 24 and to close its contacts 25. Therefore, the receiving control relay27 continues operated over a circuit formed through the contacts 22 and 25 of the relays 20 and 23, respectively. Assumin now that during the'time the equipment is in the position shown in the drawing the key i at the first station will be opened for the purpose of sending a will connect the positively poled battery 6 by way of the contacts 12 of the relay 10 to the outgoing connective point of the duplex equipment and this battery will form an accumulative series with the negatively poled battery 36 at the .distant station. At the latter station, the relay 20 will accordingly be biased to close its contacts 22, whilecurrent from the battery 36by way of the derived circuit conductor 50 will be holding the relay 55 to its negative bias and in turn the polar relay 23 will be held on the same bias to separate its contacts 25 and to close its contacts 24. Therefore, the relay 27 will then be open-circuited at the contacts 25 of the relay 23 and accordingly its con tacts will separate'to release the sounder 30. If now the transmitter 40 causes the pole-changer 33 to be operated during the time the key 1 continues in its open position, a first action takes place, due to the positively poled battery 37 atthe second station forming a differential balance with the positive battery 6 at the first station to cause relay 10 to close its contacts 13. Thereupon a second action due to the'negatively poled battery 5 connected over the contacts 13 of the relay 10 causes the line relay 20 to close its contacts 21. Coincident with this operation of the relay 20, positive current from the battery 37 will establish positive bias of the relay 55 and in turn a similar bias of the relay 23 will take place. Accordingly,the relay 27 will continue on open circuit at the separated contacts 2% of the relay 23.

The plus and minus signs adjacent the armatures of the line relays 10 and 20 indicate the. bias which these armatures will assume under the effects of the polarities from the batteries of they distant station respectively, and therefore, in the many involved duplex effects the home batteries, in

general, affect the relays inversely to such relay 27 will continue denergized; these operations being effective irrespective of urrents controlled by the t itt 4 message impulse. This position of key 1 which may be passing from the station B to the station A and in turn retransmitted to return from the station A t'othe station B, as already described.

From the foregoing description it will be obvious that, during the time non-message or unintelligible current impulses controlled by the automatic transmitter ll) may be active in both directions over the line conductor L, message impulses from the station A may also become effective through inoments of like or differential current phase action in the line L in such a manner that, irrespective of an intricately jumbled rela tion of the extraneous impulses, the message -impulses, although intermingled therewith,

may be automatically differentiated therefrom and recomposed into their original message form through the operation of the receiving devices as described.

Referring to Fig. 2 of the drawing, the arrangement shown therein relates to an alternate arrangement for controlling the operation of the retarded relay In this control the distributer equipment, already described, is provided with five additional segments 44, a collector ring at and a brush 46. By applying suitable orientation to the segments 44 and ring they may be positioned a sufiicient distance to the rear of the segments 4L1 and ring 42 to permit the brush $6 to successively join the segments 44 with the ring 45 and thereby effect operation of the relay 55, connected from the collector ring 15, in phase with the operation of the relay 20 as caused by the returning impulses etransmitted from the station A to the station B as already described.

In this alternate arrangement it will be understood that the contacts of the trans-c mitter 40 are to be connected to the segments 41, while the other portions of the local circuit may also be connected as shown in the first figure of the drawing. The currents prepared at the contacts 40 therefore energize the segments as as well as the ments il. The derived circuit lead would, of course, be dispensed with and the armature of the relay may be connected to control the relay 23, as shown in the first figure of the drawing. The ground at the battery 34: permits completion of the open ating circuit through the relay 55. It will also be clear that with this alternate arrangement for delaying the response of the relay 55, the network formed of the units 51, 52, 53 and 54 may be dispensed with and also that the service results will correspond with those already described in connection with the first arrangement, whereby the relay 23 is controlled to operate in phase with the operation of the relay 20 as effected by impulses controlled by the transmitter 40.

It may be pointed out that the key 32 at station E is ordinarily employed for the purpose of sending so-callec break signals to the station A. As well understood in the art, such break signals usually relate to requests tor repetition of some portion of a message which may be under transmission,

etc. From the foregoing description it will be obvious, however, that impulses trans mitt-ed by means of the key 32, in addition to working the relay 15 at the first station, also operate the relay l0 and thereby cause these impulses to be retransmitted to return fromthe first to the second station, without affecting the reproduction of the message at the sounder 16.

\Vhat is claimed is:

1. In a system of secret telcgraphy, a plurality of stations, a line conductor joining said stations, means for telegraphing from one of said stations to another over said line conductor, means at one of said stations for transmitting current impulses to another of said stations, and means at said last--n1entioned station for retransmitting those current impulses back to the first-mentioned station during said telegraphing.

2. In a system of secret telegraphy, a first and a second station, a line conductor joining said stations, duplex equipment for said line at each station, first means for trans mitting impulses from the first to the second of said stations, means at the second station controlled by said impulses to retransmit corresponding impulses from said second station back to said first station, means at said first station for the reception of said re turned impulses, impulse controlled means at the first station controlled in the operation of transmitting said impulses to operate in unison with said means for the reception of said returned impulses, means for transmitting message signals from said second station to said first station, means at the station for the reception of said message signals, and means controlled by said im pulse controlled means at said first station for rendering said message signals effective with said receiving means.

3. In a system of secret telegraphy,a first and a second station, a line conductor joining said stations, means for transmitting impulses from said first to said second. station, means for retransmitting corresponding impulses from said second to said first station, impulse receiving means at said first station, a plurality of electro-responsive devices-at said first station to render said retransmitted impulses non-efiective with said receiving means, transmitting means at said second station to control one or said electroresponsive devices at said first station,v and means controlled by said elec.:ro-responsive device to control the operation of said impulse receiving means.

In witness whereof I hereunto subscribe my name this ninth day of July, A. D., 1918.

GEORGE C. CUMMINGS. 

